01

Why this matters

Distributed systems share core patterns with single-machine systems.

When faced with an unfamiliar design problem, starting simple builds clarity.

A small, focused solution reveals essential components and interactions.

This foundation supports scaling to distributed architectures.


02

Start with a single-machine design

Begin by designing a solution that runs on one machine.

Identify key components such as classes, libraries, and threads.

Use standard programming constructs to model the system.

This approach ensures you understand the core logic before scaling.


03

Map components to distributed services

Each single-machine component has a distributed counterpart.

For example:

  • A thread becomes a service instance
  • A class becomes a service or module
  • A library becomes a shared component

Identify which elements need to be split into standalone services.

This mapping guides the distributed architecture.


04

Use a monolith-first approach

Design a monolith that includes all components.

Then, gradually convert it into microservices.

This bottom-up method builds a clear, structured foundation.

It helps avoid overcomplicating early design phases.


05

Apply in interviews

When designing an unfamiliar system, start with a simple solution.

This strategy generates concrete ideas and keeps the conversation focused.

It is especially useful when no other approach is immediately clear.


Questions

  • How do classes in a single-machine design map to services in a distributed system?
  • What specific components should be converted to standalone services?
  • Why is a monolith a useful starting point in system design?
  • Can you name one example of a single-machine component that becomes a service?
  • How does starting with a single machine help avoid design overcomplication?
  • What is the role of threads in a single-machine design?
  • How does this approach support system design interviews?

Key takeaways

  • Start with a single-machine solution.
  • Design using classes, libraries, and threads.
  • Map each component to a distributed service.
  • Begin with a monolith, then decompose into microservices.
  • This bottom-up approach simplifies early design decisions.
  • It is effective in interviews when no other idea exists.